Golf ball

ABSTRACT

A golf ball comprising a core and a cover layer, wherein the cover layer provides one or more deep dimples that extend through the cover layer to and/or into a layer or component underneath is disclosed. The cover may be a single layer or it may include multiple layers. If the cover is a multi-layer cover, the dimples extend to or into at least the first inner cover layer, and may extend to and/or into two or more inner cover layers. If the cover is a single layer, the dimples extend to and/or into the core. The cover layer(s) may be formed from any material suitable for use as a cover, including, but not limited to, ionomers, non-ionomers and blends of ionomers and non-ionomers. The dimples may be spherical or non-spherical, and the portion of the dimple that extends to or into the next inner layer may be the same or different shape as the outer portion of the dimple. Optionally, a moisture barrier layer may be present between the core and/or the cover layer(s).

CROSS REFERENCES TO RELATED APPLICATIONS

The present application claims priority upon U.S. ProvisionalApplication Ser. No. 60/337,123, filed Dec. 4, 2001; U.S. ProvisionalApplication Ser. No. 60/356,400, filed Feb. 11, 2002; and U.S.Provisional Application Ser. No. 60/422,422, filed Oct. 30, 2002.

FIELD OF THE INVENTION

The present invention relates to golf balls, and more particularly togolf balls having one or more deep dimples that extend through the outercover layer to and/or into one or more layers or components thereunder.

BACKGROUND OF THE INVENTION

A number of one-piece, two-piece (a solid resilient center or core witha molded cover), and multi-layer (liquid or solid center and multiplemantle and/or cover layers) golf balls have been produced. Differenttypes of materials and/or processing parameters have been utilized toformulate the cores, mantles, covers, etc. of these balls whichdramatically alter the balls' overall characteristics.

For certain applications it is desirable to produce a golf ball having avery thin cover layer. However, due to material and/or equipmentlimitations, it is often very difficult to mold a thin cover.Accordingly, it would be beneficial to provide a technique for producinga relatively thin outer cover layer.

Moreover, retractable pins have been utilized to hold, or center, thecore or core and mantle and/or cover layer(s) in place while molding anouter cover layer (or potentially other layers) thereon. These pins areretracted during the latter stages of the molding process with the stillsomewhat fluid cover or mantle material filling the void left by thepins.

The retractable pins, however, sometimes produce centering difficultiesand cosmetic problems (i.e. pin flash, pin marks, etc.) in the lands ordimples during retraction, which in turn require additional handling toproduce a golf ball suitable for use and sale. Additionally, the lowerthe viscosity of the mantle and/or cover materials, the greater thetendency for the retractable pins to stick due to material accumulation,making it necessary to shut down and clean the molds routinely.Furthermore, the pins also produce a “cold weld” when their voids arefilled during molding. This is deleterious to durability as the covermay fail by cracking through the filled pin voids after many hits.

Accordingly, it would also be desirable to provide a method for forminga thin outer cover layer or intermediate layer on a golf ball withoutthe use of retractable pins.

SUMMARY OF THE INVENTION

One aspect of the invention is to provide a golf ball having a dimpledcover that is thinner than traditional cover layers. The ball alsoproduces a favorable combination of spin, resiliency and durabilitycharacteristics.

Another aspect of the invention is to provide a golf ball having one ormore dimples in a relatively thin outer cover layer that extend to,and/or into at least the next inner layer or core of the ball. The coverlayer has an outer surface and defines a plurality of dimples along theouter surface of the cover layer. At least one of the dimples is definedby the cover layer such that the dimple extends through the cover layer.The ball may optionally comprise a thin barrier coating between thecover and the core that limits the transition of moisture to the core.

The present invention also provides, in a further aspect, a golf ballcomprising a core, a mantle layer disposed on the core, and a coverlayer disposed on the mantle layer. The cover layer has an outer surfaceand defines a plurality of dimples along the outer surface of the coverlayer. At least one of the dimples is defined by the cover layer, themantle layer, and the core such that the dimple extends through thecover layer to and/or into the mantle layer or core.

In another aspect, the present invention provides a golf ball comprisinga core and a cover layer disposed about the core. The cover layerdefines a plurality of dimples. At least a portion of the plurality ofdimples extends through the cover layer to and/or into the core. Thedimple depth is from about 0.002 inches to about 0.140 inches. The ballis preferably produced without the use of retractable pins.

An additional aspect of the present invention is to provide to a golfball with a thin cover and one or more deep dimples which extend throughthe cover layer. The ball has a favorable combination of playabilityproperties yet which may be manufactured more cost effectively andwithout the use of retractable pins and/or problems associated withprior balls.

The invention accordingly comprises several compositions, components andsteps and the relation of one or more of such compositions, componentsand steps with respect to each other. Moreover, the invention isdirected to articles possessing the features, properties, and therelation of elements exemplified in the following detailed disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The following is a brief description of the drawings, which arepresented for the purposes of illustrating the present invention and notfor the purposes of limiting the same.

FIG. 1 is a cross-sectional view of a preferred embodiment golf ballaccording to the present invention having a core and a single coverlayer having dimples, wherein one or more of the dimples extends throughthe cover to and/or into the underlying core;

FIG. 2 is a diametrical cross-sectional view of the preferred embodimentgolf ball illustrated in FIG. 1;

FIG. 3 is a cross-sectional view of another preferred embodiment golfball according to the present invention having a core component and acover component, wherein the cover component includes an inner coverlayer and an outer cover layer having dimples formed therein, andwherein one or more of the dimples of the outer cover layer extends toand/or into the underlying inner cover layer;

FIG. 4 is a diametrical cross-sectional view of the preferred embodimentgolf ball illustrated in FIG. 3;

FIG. 5 is a cross-sectional detail view of a portion of a preferredembodiment golf ball according to the present invention having a coreand a cover illustrating a dual radius dimple that extends through thecover into the underlying core;

FIG. 6 is a cross-sectional detail view of a portion of a preferredembodiment golf ball according to the present invention having a coreand a cover illustrating a dual radius dimple that extends through theouter cover layer to the outer surface of the core;

FIG. 7 is a cross-sectional detail view of a portion of a preferredembodiment golf ball according to the present invention having a core,an inner cover layer, and an outer cover layer, wherein the outer coverlayer has a dual radius dimple that extends into the inner cover layer;

FIG. 8 is a cross-sectional detail view of a portion of a preferredembodiment golf ball according to the present invention having a core,an inner cover layer, and an outer cover layer illustrating a dualradius dimple that extends through the outer cover layer to the innercover layer of the ball;

FIG. 9 is a top view of a preferred embodiment golf ball according tothe present invention having a first population of typical dimples alongwith three deeper dimples configured in a triangular pattern about thepole of the ball;

FIG. 10 is a top view of a preferred embodiment golf ball according tothe present invention having a first population of typical dimples alongwith four deeper dimples arranged in a diamond pattern about the pole ofthe ball;

FIG. 11 is a cross-sectional detail view of a portion of a preferredembodiment golf ball according to the present invention having a core,an inner cover or mantle layer, and an outer cover layer illustrating adimple that extends through the outer cover layer to the mantle layer;

FIG. 12 is a top view of a portion of a preferred embodiment golf ballaccording to the present invention having a cover with dimples formed intwo layers of the cover and illustrating an inner dimple portion formedin the inner cover layer and an outer dimple portion formed in the outercover layer;

FIG. 13 is a graph illustrating the relationship between the location ona golf ball of certain dimples according to the invention and theresulting forces in a self-supporting cavity during molding;

FIG. 14 is a perspective view of a golf ball illustrating a regiondefined along the outer surface of the ball; and

FIG. 15 is a schematic view of a preferred embodiment molding assemblyand a golf ball core according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention relates to improved golf balls, particularly agolf ball comprising a cover having one or more layers disposed about acore. The cover has one or more, preferably a plurality of, deep dimplesor apertures that extend through the outer cover to and/or into, orthrough, one or more layers underneath. The core can be a wound core, anenclosed liquid or hollow core, a metal or a solid core, or the like,with a solid core being the more preferred. The golf balls of thepresent invention, which can be of a standard or enlarged size, have aunique combination of cover layer thicknesses and dimple configuration.

As explained in greater detail herein, the present invention alsorelates to the use of one or more “deep dimples.” These deep dimpleshave depths greater than other dimples on a ball. Such deep dimplesextend through at least one cover layer to, and/or into, the underlyingsurface, component or layer of the ball.

With regard to dimple configuration or cross-sectional geometry, thepresent invention is based upon the identification of variousparticularly preferred characteristics as follows. Typically, forcircular dimples, dimple diameter is used in characterizing dimple sizerather than dimple circumference. The diameter of typical dimples mayrange from about 0.050 inches to about 0.250 inches. A preferreddiameter of a typical dimple is about 0.150 inches. The deep dimples mayhave these same dimensions or may have dimensions as described ingreater detail herein. As will be appreciated, circumference of a dimplecan be calculated by multiplying the diameter times π.

The depth of typical dimples previously utilized in the trade may rangefrom about 0.002 inches to about 0.020 inches or more depending upon thecover thickness and/or flight characteristics desired. A depth of about0.010 inches is typical for conventional dimples. These dimples areutilized on golf balls having typical outer cover thicknesses of 0.030to 0.100 inches.

However, the depth of a deep dimple of the present invention asdescribed herein is greater than the depth of a typical or conventionaldimple. Preferably, the deep dimples extend through at least the outercover layer of the ball. More preferably, the deep dimples have a depththat is deeper than the depth of the typical dimples by at least 0.002inches.

In this regard, in a traditional prior art ball, the dimple depth, whichis generally about 0.010 inches, is less than the thickness of the coverso that the dimple does not touch or extend to the next layer or evencome close to the next layer. Therefore, there is a minimum coverthickness that can be used in order to have dimples of the desireddepth. The golf ball of the present invention eliminates the need tohave a cover thickness greater than the desired dimple depth because oneor more layers can make up the dimple, and thus, each layer may be verythin (less than 0.010 inches).

Specifically, depth of a dimple may be defined in at least two fashions.A first approach is to extend a chord from one side of a dimple toanother side and then measure the maximum distance from that chord tothe bottom of the dimple. This is referred to herein as a “chordaldepth.” Alternatively, another approach is to extend an imaginary linecorresponding to the curvature of the outer surface of the ball over thedimple whose depth is to be measured. Then, the distance from thatimaginary line to a bottom most point in the dimple is measured. This isreferred to herein as a “periphery depth.” The latter format of dimpledepth determination is used herein unless noted otherwise.

As described in more detail below, the deep dimples included in thepresent invention are particularly useful when molding certain layers orcomponents about cores or intermediate ball assemblies. The depth (i.e.periphery depth) of a deep dimple as described herein may range fromabout 0.002 inches to about 0.140 inches, more preferably from about0.002 inches to about 0.050 inches, and more preferably from about 0.005inches to about 0.040 inches. Preferably, a total depth of about 0.025inches is desired. The depth of a deep dimple as described herein isgreater than the depth of a typical dimple, and extend to at least theoutermost region of the mantle or core. Alternatively, the deep dimplesmay also extend to the bottom of a matched set of dimples on the mantleor the core. Generally, depth is given with respect to periphery depthfrom the outer surface of a finished ball, unless stated otherwise.

The diameter of the deep dimples may be dissimilar, but preferably isthe same as other dimples on a ball, and may range from about 0.025inches to about 0.250 inches and more preferably from about 0.050 inchesto about 0.200 inches. A preferred diameter is about 0.150 inches.

In a further embodiment, the present invention relates to a golf ballcomprising a core and a cover layer, wherein the cover layer providesdimples including one or more deep dimples that extend into or throughthe next inner layer or component. The cover may be a single layer ormay comprise multiple layers, such as two, three, four, five or morelayers and the like. If the cover is a multi-layer cover, the dimplesextend to or into at least the first inner cover layer, and may extendinto or through a further inner cover layer, a mantle or intermediatelayer, and/or the core. If the cover is a single layer, the deep dimplesmay extend into or through a mantle layer to the core. The coverlayer(s) may be formed from any material suitable for use as a cover,including, but not limited to, ionomers, non-ionomers and blends ofionomers and non-ionomers.

In another embodiment, the present invention relates to a golf ballcomprising a core and a cover layer, wherein the cover layer providesdimples that extend to the outer surface of the core. The golf ball mayoptionally comprise a thin barrier coating between the core and thecover that limits the transition of moisture to the core. The barriercoating is preferably at least about 0.0001 inches thick. Preferably,the barrier layer is at least 0.003 inches thick. In a two piece golfball, a barrier coating is preferably provided between the core and thecover.

In a further embodiment, the present invention relates to a golf ballhaving a plurality of dimples along its outer surface. In accordancewith the present invention, one or more of these dimples, preferably twoor more of the dimples, and more preferably three or more of thedimples, are deep dimples that extend entirely through the cover layerof the ball, and into one or more underlying components or layers of theball. For instance, for a golf ball comprising a core and a cover layerdisposed about the core, the deep dimples preferably extend through thecover layer and into the core.

Additionally, the core or mantle layer may be “dimpled” such that thedimples on the core or mantle match up with and accept the “deep”dimples from the mold. If one or more layers such as an intermediatemantle layer are provided between the core and the cover layer, the deepdimples preferably extend through the cover layer and into and/orthrough one or more of those layers. The deep dimples may additionallyextend into the core.

The deep dimples of the present invention may be spherical ornon-spherical. Additionally, the portion of the deep dimple that extendsto, or into the next inner layer or component may be the same ordifferent size and/or shape as the outer portion of the dimple.

Moreover, the deep dimples of the present invention can also be utilizedto enhance treatment (i.e., deburring, painting, printing, etc.) of themolded ball. For example, the deep dimple can be utilized to hold or fixthe molded ball for surface modifications and/or coating.

FIGS. 1 and 2 illustrate a preferred embodiment golf ball in accordancewith the present invention. Specifically, FIGS. 1 and 2 illustrate agolf ball 10 comprising a core 20 having a cover layer 30 formed aboutthe core. The cover layer 30 defines a plurality of dimples 40 along itsouter surface 35. One or more of the dimples, and preferably two or moreof the dimples, extend into the core 20 disposed underneath the coverlayer 30. These dimples are herein referred to as deep dimples and shownin the figures as dimples 42.

FIGS. 3 and 4 illustrate another preferred embodiment golf ball 110 inaccordance with the present invention. The golf ball 110 comprises acore 120 having an inner cover layer 150 disposed thereon and an outercover layer 160 formed about the inner cover layer 150. The cover layers160 and 150 define a plurality of dimples 140 along the outer surface ofthe outer cover layer 160. One or more of the dimples, and preferablytwo or more of the dimples, and more preferably three or more of thedimples per hemisphere, extend entirely through the outer cover layer160 and at least partially into the inner cover layer 150. Thesedimples, which extend through the outer cover layer, are again referredto herein as deep dimples and shown in the figures as dimples 142.

FIG. 11 illustrates a partial cross section of a golf ball 810 defininga deep dimple 850 formed in an outer cover layer 820 disposed on amantle (or inner cover) layer 830 that in turn is disposed on a core840. The deep dimple 850 has a common curvature. Alternatively, the deepdimples or depressions may be defined by regions of different curvatureor shape. This is described in greater detail below.

The deep dimples can be circular, non-circular, a combination ofcircular and non-circular, or any other shape desired. They may be ofthe same or differing shape, such as a circular larger dimple having anoval smaller dimple within the circular dimple, or an oval larger dimplehaving a circular or other shape within the larger dimple. The dimplesdo not have to be symmetrical.

Providing deep dimples formed in multiple layers allows the dimple depthto be spread over two or more layers. FIG. 12 illustrates dimples 940formed in both the inner cover layer and the outer cover layer. Theinner portion of the dimple 946 is formed in the inner cover layer, andthe outer portion of the dimple 948 is formed in the outer cover layer.For a two piece ball, dimples may be formed in the core and the singlecover layer in the same way as previously described. Additionally,dimples may be formed in more than two cover and/or core layers ifdesired.

In another preferred embodiment, a multi-layer golf ball is producedthat has one or more deep dimples that protrude into the ball through atleast one layer, such as an outer cover layer. In a further preferredembodiment, the deep dimple protrudes through at least two layers. Thedimples of the at least two layers are configured with the samegeometric coordinates (that is, the approximate center of both dimpleswould be in the same location, and so the dimples are concentric withrespect to each other), producing a golf ball having a dimpled layerover a dimpled layer. This allows for much thinner layers withtraditional dimples. The dimples of one or more inner layers may be ofvarying depths, diameters and radii, yet still aligned with the dimplesof the outer layer. This also allows for a dimple within a dimple, wherethere is a smaller dimple in at least one inner or mantle layer that iswithin a larger diameter dimple in the outer layer, such as the dimplesshown in FIGS. 5 to 8.

FIGS. 5 to 8 illustrate a deep dimple that is a dual radius dimple, adual region dimple, or a dimple within a dimple (these terms aregenerally used interchangeably herein). One advantage of a dual radiusdimple is that the deeper part of the dual radius may be filled in witha coating or other material. This provides an effective method forforming dimple depths to a desired value as compared to other methods ofdimple formation. The dimple shape may be any shape desired, and eachdimple may be the same or different shape. The shape of a dimple orregion thereof is given when viewed in a direction extending along adiameter of the golf ball. The respective regions of the dual regiondimples may be in a variety of different (or the same) shapes such ascircular, elliptical, oval, square, triangular, and polygonal.

Preferably, the depth of the second or deepest portion of the dualradius dimple may be expressed as a percentage of the total depth of thedimple. Specifically, the region or portion of the dimple which extendsto the outermost surface of the ball may be referred to herein as the“major” dimple. And, likewise, the portion of the dimple which extendsto the deepest portion or depth of the dimple can be referred to hereinas the “minor” dimple. Accordingly, the preferred depth of the majordimple is approximately from about 40% to about 80% of the overalldimple depth. Accordingly, the preferred depth of the minor dimple isapproximately 20% to about 60% of the overall dimple depth. The depth ismeasured from the chord of the major dimple extending between the majorand minor portions to the bottom of the minor dimple. As explained ingreater detail herein, this is the “chordal depth” since this depth istaken with regard to a chord extending across a span of the dimple. Withregard to diameters, the preferred diameter of the minor dimple is fromabout 10% to about 70% of the diameter of the major dimple.

FIG. 5 is a cross-sectional detail illustrating a portion of a preferredembodiment golf ball in accordance with the present invention. Thispreferred embodiment golf ball 210 comprises a core 220 having a coverlayer 230 formed thereon. The cover layer defines at least one deepdimple 240 along its outer surface 235. As described in conjunction withFIGS. 1 and 2, it is preferred that one or more (preferably two or more,more preferably three or more per hemisphere) of the dimples extendsentirely through the cover layer and into the core disposed underneaththe cover layer.

FIG. 5 further illustrates a deep dimple defined by two differentcurvatures. Referring to FIG. 5, a first radius R₁ defines the portionof the dimple from the outer surface 235 of the golf ball 210 to a pointat which the deep dimple extends into a layer underneath the coverlayer. At this point, the curvature of the dimple changes and is definedby radius R₂.

Preferably, R₁,is from about 0.130 inches to about 0.190 inches, andmost preferably, R₁, is from about 0.140 to about 0.180 inches. For someembodiments, R₁ ranges from about 0.100 inches to about 1.000 inch, andmost preferably from about 0.200 inches to about 0.800 inches.

Preferably, R₂ is from about 0.025 inches to about 0.075 inches, andmost preferably, R₂ is about 0.050 to about 0.065 inches. For someembodiments, R₂ ranges from about 0.002 inches to about 0.50 inches, andmost preferably from about 0.010 inches to about 0.200 inches.

The overall diameter or span, generally referred to as the “majorchordal diameter,” of the dimple 240 is designated herein as D₁. Thediameter or span, generally referred to as the “minor chordal diameter,”of the portion of the dimple that extends into the layer underneath theouter cover layer is designated herein as D₂.

Preferably, D₁ is from about 0.030 inches to about 0.250 inches, morepreferably from about 0.100 inches to about 0.186 inches, and mostpreferably, D₁ is about 0.146 inches to about 0.168 inches. For someembodiments, D₁ ranges from about 0.100 inches to about 0.250 inches,and most preferably D₁ is about 0.140 inches to about 0.180 inches.

Preferably D₂ is from about 0.020 inches to about 0.160 inches, morepreferably from about 0.030 inches to about 0.080 inches, and mostpreferably, D₂ is about 0.056 inches. For some embodiments, D₂ is fromabout 0.040 inches to about 0.060 inches.

Accordingly, the overall depth of the deep dimple portion that isdefined by R₁ is designated herein as H₁ and the depth or portion of thedimple that is defined by R₂ is designated herein as H₂. Preferably, H₁is from about 0.005 inches to about 0.135 inches, more preferably fromabout 0.005 to about 0.025 inches, more preferably from about 0.010inches to about 0.015 inches, and most preferably, H₁ is about 0.015inches. For some embodiments, H₁ is from about 0.005 inches to about0.015 inches. H₂ may range from about 0.005 inches to about 0.135inches, and more preferably from about 0.005 to about 0.050 inches.Preferably, H₂ ranges from about 0.005 inches to about 0.030 inches andis about 0.010 inches. For some embodiments, H₂ is from about 0.005inches to about 0.015 inches.

Referring to FIG. 6, another preferred embodiment golf ball 310 isillustrated. In this version of the present invention, a golf ball 310comprises a core 320 and a cover layer 330 formed thereon. The coverlayer 330 defines at one deep dimple 340 along the outer surface 335 ofthe golf ball 310. As can be seen, the dimple 340 is defined by twodifferent curvatures, each of which is defined by radii R₂ and R₁ aspreviously described with respect to FIG. 5. The other parameters D₁,D₂, H₁, and H₂ are as described with respect to FIG. 5. FIG. 6illustrates an embodiment in which the dimple 340 extends to the core320 and not significantly into the core. In contrast, the versionillustrated in FIG. 5 is directed to a dimple configuration in which adimple extends significantly into the underlying core.

FIG. 7 illustrates a preferred embodiment golf ball 410 comprising acore 420, a mantle or inner cover layer 450, and an outer cover layer460. The outer cover layer 460 defines at least one deep dimple 440along the outer surface 435 of the ball 410. The dimple 440 is definedby two different regions or two curvatures, each of which is in turndefined by radii R₂ and R₁. The other parameters D₁, D₂, H₁, and H₂ areas described with respect to FIG. 5. As can be seen in FIG. 7, thedimple 440 extends entirely through the outer cover layer 460 and intothe inner cover layer or mantle layer 450.

FIG. 8 illustrates another preferred embodiment golf ball 510 inaccordance with the present invention. The golf ball 510 comprises acore 520 having disposed thereon an inner cover layer or mantle layer550 and an outer cover layer 560. Defined along the perimeter or outerperiphery of the ball 510 is at least one deep dimple 540. The dimple540 is defined along the outer surface 535 of the ball 510. The dimple540 has two different regions or curvatures each defined by radii R₂ andR₁, as previously described. The other parameters D₁, D₂, H₁, and H₂ areas described with respect to FIG. 5. The version illustrated in FIG. 8reveals a dimple 540 that does not significantly extend into the mantlelayer or inner cover layer 550. Instead, the dimple 540 only extends tothe outermost region of the mantle layer or inner cover layer 550.

In the various dual-radius dimples, dual region dimples, ordimples-within-dimples described herein, the present invention includesfilling either or both of the regions with various materials. The fillermaterials are preferably different than cover materials, but may includesuch. Preferably, the filler materials incorporate one or more coloringagents.

An important characteristic of dimple configuration is the volume ratio.The volume ratio is the sum of the volume of all dimples taken below achord extending across the top of a dimple, divided by the total volumeof the ball.

The volume ratio is a critical parameter for ball flight. A high volumeratio generally results in a low flying ball. And a low volume ratiooften results in a high-flying ball. A preferred volume ratio is about1%. The balls of the present invention however may be configured withgreater or lesser volume ratios.

The number and/or layout of dimples will not necessarily change thecoverage, i.e. surface area. A typical coverage for a ball of thepresent invention is about 60% to about 95% and preferably about 83.8%.In other embodiments, this preferred coverage is about 84% to about 85%.These percentages are the percent of surface area of the ball occupiedby dimples. It will be appreciated that the present invention golf ballsmay exhibit coverages greater or less than that amount.

For configurations utilizing dimples having two or more regions ofdifferent curvature, i.e. dimple within a dimple, there is less impacton the volume ratio than the use of deep dimples. If there are enough ofeither dimples within dimples or deep dimples, that will eventuallyimpact the aerodynamics of the ball will eventually be impacted.

The optimum or preferred number of deep dimples utilized per ballvaries. The preferred number is the amount necessary to secure or centerthe core during molding without adversely affecting the aerodynamics ofthe finished ball. However, the present invention includes the use of arelatively large number of deep dimples. That is, although most of thefocus of the present invention is directed to the use of only a few deepdimples per golf ball, i.e. from 1 to 10, preferably 1 to 8, morepreferably 1 to 6, the invention includes the use of a significantlygreater number such as from about 50 to about 250. It is alsocontemplated that for some applications, it may be desirable to formall, or nearly all, dimples on a golf ball as deep dimples, such as forexample, from about 50 to about 500.

In general, as dimples are made deeper, the ball will fly lower ascompared to the use of dimples that are shallower. As the number of deepdimples increases, the ball will exhibit a lower flight trajectory.Accordingly, the preferred approach is to utilize a smaller or fewernumber of deep dimples. However, for other applications, the presentinvention includes a ball with many deep dimples.

During molding, deep dimples can impregnate the core or mantle.Generally, the deep dimples will extend into the core from the moldingcavity and contact the core. But, the core will rebound back to itsoriginal shape to some extent so that the volume of the dimple at thepoint of contact is less than would otherwise be expected. This isexplained in greater detail below.

The overall shape of the dimples, including deep dimples, may be nearlyany shape. For example, shapes such as hexagon, pentagon, triangle,ellipse, circle, etc. are all suitable. There is no limit to the numberof shapes, although some shapes are preferred over others. At present,circular dimples are preferred. As for the cross-sectionalconfiguration, the dimples may utilize any geometry. For instance,dimples may be defined by a constant curve or a multiple curvature ordual radius configuration or an elliptical or teardrop shaped region.

Cover Layer(s)

The cover comprises at least one layer. For a multi-layer cover, thecover comprises at least two layers, and it may comprise any number oflayers desired, such as two, three, four, five, six and the like. A twopiece cover comprises a first or inner layer or ply (also referred to asa mantle layer) and a second or outer layer or ply.

The inner layer can be ionomer, ionomer blends, non-ionomer, non-ionomerblends, or blends of ionomer and non-ionomer. The outer layer can beionomer, ionomer blends, non-ionomer, non-ionomer blends, or blends ofionomer and non-ionomer, and may be of the same or different material asthe inner cover layer. For multi-layer covers having three or morelayers, each layer can be ionomer, non-ionomer, or blends thereof, andthe layers may be of the same or different materials.

In another preferred embodiment of a golf ball, the inner layer orsingle cover layer is comprised of a high acid (i.e. greater than 16weight percent acid) ionomer resin or high acid ionomer blend. Morepreferably, the inner layer is comprised of a blend of two or more highacid (i.e. greater than 16 weight percent acid) ionomer resinsneutralized to various extents by different metal cations. The innercover layer may or may not include a metal stearate (e.g., zincstearate) or other metal fatty acid salt. The purpose of the metalstearate or other metal fatty acid salt is to lower the cost ofproduction without affecting the overall performance of the finishedgolf ball.

In a further embodiment, the inner layer or single cover layer iscomprised of a low acid (i.e. 16 weight percent acid or less) ionomerresin or low acid ionomer blend. Preferably, the inner layer or singlelayer is comprised of a blend of two or more low acid (i.e. 16 weightpercent acid or less) ionomer resins neutralized to various extents bydifferent metal cations. As with the high acid inner cover layerembodied, the inner cover layer may or may not include a metal stearate(e.g., zinc stearate) or other metal fatty acid salt.

In golf balls having a multi-layer cover, it has been found that a hardinner layer(s) and/or low driver spin provides for a substantialincrease in resilience (i.e., enhanced distance) over known multi-layercovered balls. A softer outer layer (or layers) provides for desirable“feel” and high spin rate while maintaining respectable resiliency. Thesoft outer layer allows the cover to deform more during impact andincreases the area of contact between the club face and the cover,thereby imparting more spin on the ball. As a result, the soft coverprovides the ball with a balata-like feel and playabilitycharacteristics with improved distance and durability. Consequently, theoverall combination of the inner and outer cover layers results in agolf ball having enhanced resilience (improved travel distance) anddurability (i.e. cut resistance, etc.) characteristics while maintainingand in many instances, improving, the playability properties of theball.

The combination of a hard inner cover layer with a soft outer coverlayer provides for excellent overall coefficient of restitution (forexample, excellent resilience) because of the improved resiliencyproduced by the inner cover layer. While some improvement in resiliencyis also produced by the outer cover layer, the outer cover layergenerally provides for a more desirable feel and high spin, particularlyat lower swing speeds with highly lofted clubs such as half wedge shots.

In one preferred embodiment, the inner cover layer may be harder thanthe outer cover layer and generally has a thickness in the range of0.0005 to 0.15 inches, preferably 0.001 to 0.10 inches for a 1.68 inchball, and sometimes slightly thicker for a 1.72 inch (or more) ball. Thecore and inner cover layer (if applicable) together preferably form aninner or intermediate ball having a coefficient of restitution of 0.780or more and more preferably 0.790 or more, and a diameter in the rangeof 1.48 to 1.66 inches for a 1.68 inch ball and 1.50 to 1.70 inches fora 1.72 inch (or more) ball.

The inner cover layer preferably has a Shore D hardness of 60 or more(or at least 90 Shore C). It is particularly advantageous if the golfballs of the invention have an inner layer with a Shore D hardness of 65or more (or at least 100 Shore C). These measurements are made ingeneral accordance to ASTM 2240 except that they are made on the ballitself and not on a plaque. If the inner layer is too soft or thin, itis sometimes difficult to measure the Shore D of the inner layer as thelayer may puncture during measurement. In such circumstances, analternative Shore C measurement should be utilized. Additionally, if thecore (or inner layer) is harder than the layer being measured, this willsometimes influence the reading.

Moreover, if the Shore C or Shore D is measured on a plaque of material,different values than those measured on the ball will result.Consequently, when a Shore hardness measurement is referenced to herein,it is based on a measurement made on the ball, except if specificreference is made to plaque measurements.

The above-described characteristics of the inner cover layer provide aninner ball having a PGA compression of 100 or less. It is found thatwhen the inner ball has a PGA compression of 90 or less, excellentplayability results.

The inner layer compositions of the embodiments described herein mayinclude the high acid ionomers such as those developed by E. I. DuPontde Nemours & Company under the trademark Surlyn® and by ExxonCorporation under the trademarks Escor® or lotek®, or blends thereof.Examples of compositions which may be used as the inner layer herein areset forth in detail in U.S. Pat. No. 5,688,869, which is incorporatedherein by reference. Of course, the inner layer high acid ionomercompositions are not limited in any way to those compositions set forthin said patent. Those compositions are incorporated herein by way ofexamples only.

The high acid ionomers which may be suitable for use in formulating theinner layer compositions are ionic copolymers which are the metal (suchas sodium, zinc, magnesium, etc.) salts of the reaction product of anolefin having from about 2 to 8 carbon atoms and an unsaturatedmonocarboxylic acid having from about 3 to 8 carbon atoms. Preferably,the ionomeric resins are copolymers of ethylene and either acrylic ormethacrylic acid. In some circumstances, an additional comonomer such asan acrylate ester (for example, iso- or n-butylacrylate, etc.) can alsobe included to produce a softer terpolymer. The carboxylic acid groupsof the copolymer are partially neutralized (for example, approximately10-100%, preferably 30-70%) by the metal ions. Each of the high acidionomer resins which may be included in the inner layer covercompositions of the invention contains greater than 16% by weight of acarboxylic acid, preferably from about 17% to about 25% by weight of acarboxylic acid, more preferably from about 18.5% to about 21.5% byweight of a carboxylic acid.

The high acid ionomeric resins available from Exxon under thedesignation Escor® or lotek®, are somewhat similar to the high acidionomeric resins available under the Surlyn® trademark. However, sincethe Escor®/lotek® ionomeric resins are sodium, zinc, etc. salts ofpoly(ethylene-acrylic acid) and the Surlyn® resins are zinc, sodium,magnesium, etc. salts of poly(ethylene-methacrylic acid), distinctdifferences in properties exist. It is also contemplated to utilizecommercially available resins that have been modified withethylene/acrylic acid resins for example.

Examples of the high acid methacrylic acid based ionomers found suitablefor use in accordance with this invention include, but are not limitedto, Surlyn® 8220 and 8240 (both formerly known as forms of Surlyn®AD-8422), Surlyn® 9220 (zinc cation), Surlyn® SEP-503-1 (zinc cation),and Surlyn® SEP-503-2 (magnesium cation). According to DuPont, all ofthese ionomers contain from about 18.5 to about 21.5% by weightmethacrylic acid.

Examples of the high acid acrylic acid based ionomers suitable for usein the present invention also include, but are not limited to, theEscor® or lotek® high acid ethylene acrylic acid ionomers produced byExxon such as Ex 1001, 1002, 959, 960, 989, 990, 1003, 1004, 993, and994. In this regard, Escor® or lotek® 959 is a sodium ion neutralizedethylene-acrylic neutralized ethylene-acrylic acid copolymer. Accordingto Exxon, loteks® 959 and 960 contain from about 19.0 to about 21.0% byweight acrylic acid with approximately 30 to about 70 percent of theacid groups neutralized with sodium and zinc ions, respectively.

Furthermore, as a result of the previous development by the assignee ofthis application of a number of high acid ionomers neutralized tovarious extents by several different types of metal cations, such as bymanganese, lithium, potassium, calcium and nickel cations, several highacid ionomers and/or high acid, ionomer blends besides sodium, zinc andmagnesium high acid ionomers or ionomer blends are also available forgolf ball cover production. It has been found that these additionalcation neutralized high acid ionomer blends produce inner cover layercompositions exhibiting enhanced hardness and resilience due tosynergies which occur during processing. Consequently, these metalcation neutralized high acid ionomer resins can be blended to producesubstantially higher C.O.R.'s than those produced by the low acidionomer inner cover compositions presently commercially available.

More particularly, several metal cation neutralized high acid ionomerresins have been produced by the assignee of this invention byneutralizing, to various extents, high acid copolymers of analpha-olefin and an alpha, beta-unsaturated carboxylic acid with a widevariety of different metal cation salts. This discovery is the subjectmatter of U.S. Pat. No. 5,688,869, incorporated herein by reference. Ithas been found that numerous metal cation neutralized high acid ionomerresins can be obtained by reacting a high acid copolymer (i.e. acopolymer containing greater than 16% by weight acid, preferably fromabout 17 to about 25 weight percent acid, and more preferably about 20weight percent acid), with a metal cation salt capable of ionizing orneutralizing the copolymer to the extent desired (for example, fromabout 10% to 90%).

The base copolymer is made up of greater than 16% by weight of an alpha,beta-unsaturated carboxylic acid and an alpha-olefin. Optionally, asoftening comonomer can be included in the copolymer. Generally, thealpha-olefin has from 2 to 10 carbon atoms and is preferably ethylene,and the unsaturated carboxylic acid is a carboxylic acid having fromabout 3 to 8 carbons. Examples of such acids include acrylic acid,methacrylic acid, ethacrylic acid, chloroacrylic acid, crotonic acid,maleic acid, fumaric acid, and itaconic acid, with acrylic acid beingpreferred.

The softening comonomer that can be optionally included in the innercover layer of the golf ball of the invention may be selected from thegroup consisting of vinyl esters of aliphatic carboxylic acids whereinthe acids have 2 to 10 carbon atoms, vinyl ethers wherein the alkylgroups contain 1 to 10 carbon atoms, and alkyl acrylates ormethacrylates wherein the alkyl group contains 1 to 10 carbon atoms.Suitable softening comonomers include vinyl acetate, methyl acrylate,methyl methacrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate,butyl methacrylate, or the like.

Consequently, examples of a number of copolymers suitable for use toproduce the high acid ionomers included in the present inventioninclude, but are not limited to, high acid embodiments of anethylene/acrylic acid copolymer, an ethylene/methacrylic acid copolymer,an ethylene/itaconic acid copolymer, an ethylene/maleic acid copolymer,an ethylene/methacrylic acid/vinyl acetate copolymer, anethylene/acrylic acid/vinyl alcohol copolymer, etc. The base copolymerbroadly contains greater than 16% by weight unsaturated carboxylic acid,from about 39 to about 83% by weight ethylene and from 0 to about 40% byweight of a softening comonomer. Preferably, the copolymer containsabout 20% by weight unsaturated carboxylic acid and about 80% by weightethylene. Most preferably, the copolymer contains about 20% acrylic acidwith the remainder being ethylene.

Along these lines, examples of the preferred high acid base copolymerswhich fulfill the criteria set forth above are a series ofethylene-acrylic copolymers which are commercially available from TheDow Chemical Company, Midland, Mich., under the Primacor® designation.

The metal cation salts utilized in the invention are those salts whichprovide the metal cations capable of neutralizing, to various extents,the carboxylic acid groups of the high acid copolymer. These includeacetate, oxide or hydroxide salts of lithium, calcium, zinc, sodium,potassium, nickel, magnesium, and manganese.

Examples of such lithium ion sources are lithium hydroxide monohydrate,lithium hydroxide, lithium oxide and lithium acetate. Sources for thecalcium ion include calcium hydroxide, calcium acetate and calciumoxide. Suitable zinc ion sources are zinc acetate dihydrate and zincacetate, a blend of zinc oxide and acetic acid. Examples of sodium ionsources are sodium hydroxide and sodium acetate. Sources for thepotassium ion include potassium hydroxide and potassium acetate.Suitable nickel ion sources are nickel acetate, nickel oxide and nickelhydroxide. Sources of magnesium include magnesium oxide, magnesiumhydroxide, and magnesium acetate. Sources of manganese include manganeseacetate and manganese oxide.

The metal cation neutralized high acid ionomer resins are produced byreacting the high acid base copolymer with various amounts of the metalcation salts above the crystalline melting point of the copolymer, suchas at a temperature from about 200° F. to about 500° F., preferably fromabout 250° F. to is about 350° F. under high shear conditions at apressure of from about 10 psi to 10,000 psi. Other well known blendingtechniques may also be used. The amount of metal cation salt utilized toproduce the new metal cation neutralized high acid based ionomer resinsis the quantity which provides a sufficient amount of the metal cationsto neutralize the desired percentage of the carboxylic acid groups inthe high acid copolymer. The extent of neutralization is generally fromabout 10% to about 90%.

A number of different types of metal cation neutralized high acidionomers can be obtained from the above indicated process. These includehigh acid ionomer resins neutralized to various extents with manganese,lithium, potassium, calcium and nickel cations. In addition, when a highacid ethylene/acrylic acid copolymer is utilized as the base copolymercomponent of the invention and this component is subsequentlyneutralized to various extents with the metal cation salts producingacrylic acid based high acid ionomer resins neutralized with cationssuch as sodium, potassium, lithium, zinc, magnesium, manganese, calciumand nickel, several cation neutralized acrylic acid based high acidionomer resins are produced.

When compared to low acid versions of similar cation neutralized ionomerresins, the metal cation neutralized high acid ionomer resins exhibitenhanced hardness, modulus and resilience characteristics. These areproperties that are particularly desirable in a number of thermoplasticfields, including the field of golf ball manufacturing.

The low acid ionomers which may be suitable for use in formulating theinner layer compositions of the subject invention are ionic copolymerswhich are the metal (sodium, zinc, magnesium, etc.) salts of thereaction product of an olefin having from about 2 to 8 carbon atoms andan unsaturated monocarboxylic acid having from about 3 to 8 carbonatoms. Preferably, the ionomeric resins are copolymers of ethylene andeither acrylic or methacrylic acid. In some circumstances, an additionalcomonomer such as an acrylate ester (for example, iso- orn-butylacrylate, etc.) can also be included to produce a softerterpolymer. The carboxylic acid groups of the copolymer are partiallyneutralized (for example, approximately 10 to 100%, preferably 30 to70%) by the metal ions. Each of the low acid ionomer resins which may beincluded in the inner layer cover compositions of the invention contains16% by weight or less of a carboxylic acid.

The inner layer compositions may include the low acid ionomers such asthose developed and sold by E. I. DuPont de Nemours & Company under thetrademark Surlyn® and by Exxon Corporation under the trademarks Escor®or lotek®, ionomers made in-situ, or blends thereof.

In one embodiment of the inner cover layer, a blend of high and low acidionomer resins is used. These can be the ionomer resins described above,combined in a weight ratio which preferably is within the range of 10 to90 to 90 to 10 percent high and low acid ionomer resins.

Another embodiment of the inner cover layer is a cover comprising anon-ionomeric thermoplastic material or thermoset material. Suitablenon-ionomeric materials include, but are not limited to, metallocenecatalyzed polyolefins or polyamides, polyamide/ionomer blends,polyphenylene ether/ionomer blends, etc., which have a Shore D hardnessof at least 60 (or a Shore C hardness of at least about 90) and a flexmodulus of greater than about 30,000 psi, preferably greater than about50,000 psi, or other hardness and flex modulus values which arecomparable to the properties of the ionomers described above. Othersuitable materials include but are not limited to, thermoplastic orthermosetting polyurethanes, thermoplastic block polyesters, forexample, a polyester elastomer such as that marketed by DuPont under thetrademark Hytrel®, or thermoplastic block polyamides, for example, apolyether amide such as that marketed by Elf Atochem S. A. under thetrademark Pebax®, a blend of two or more non-ionomeric thermoplasticelastomers, or a blend of one or more ionomers and one or morenon-ionomeric thermoplastic elastomers. These materials can be blendedwith the ionomers described above in order to reduce cost relative tothe use of higher quantities of ionomer. Although Hytrel® and Pebax® aresometimes more expensive than certain ionomers, these materialstypically have higher densities than ionomers and have differentresiliency characteristics at low impacts, and so, may be desirable.

Additional materials suitable for use in the inner cover layer or singlecover layer of the present invention include polyurethanes. These aredescribed in more detail below.

Any number of inner layers may be used. Each layer may be the same ordifferent material as any other layer, and each may be of the same ordifferent thickness. One or more of the inner layers, if applicable, mayalso be the same as the outer cover layer.

A core with a hard inner cover layer formed thereon generally providesthe multi-layer golf ball with resilience and distance. In one preferredembodiment, the outer cover layer is comparatively softer than the innercover layer. For a golf ball having a single cover layer and a core, thecover layer may be a soft cover layer, as described herein. The softnessprovides for the feel and playability characteristics typicallyassociated with balata or balata-blend balls.

The soft outer cover layer or ply is comprised of a relatively soft, lowflex modulus (about 500 psi to about 50,000 psi, preferably about 1,000psi to about 25,000 psi, and more preferably about 5,000 psi to about20,000 psi) material or blend of materials. The outer cover layer (orsingle cover layer, if applicable) comprises ionomers, non-ionomers,blends of ionomers, blends of non-ionomers and blends of ionomers andnon-ionomers. Preferably, the outer cover layer comprises apolyurethane, a polyurea, a blend of two or morepolyurethanes/polyureas, or a blend of one or more ionomers or one ormore non-ionomeric thermoplastic materials with a polyurethane/polyurea,preferably a thermoplastic polyurethane or reaction injection moldedpolyurethane/polyurea (described in more detail below).

The outer layer is 0.0005 to about 0.15 inches in thickness, preferablyabout 0.001 to about 0.10 inches in thickness, and sometimes slightlythicker for a 1.72 inch (or more) ball, but thick enough to achievedesired playability characteristics while minimizing expense. Thicknessis defined as the average thickness of the non-dimpled areas of theouter cover layer. The outer cover layer preferably has a Shore Dhardness of 60 or less (or less than 90 Shore C), and more preferably 55or less (or about 80 Shore C or less).

In another preferred embodiment, the outer cover layer is comparativelyharder than the inner cover layer. The outer layer is comprised of arelatively hard, higher flex modulus (about 40,000 psi or greater)material or blend of materials. The inner cover layer(s) may be a softermaterial such as a polyurethane or other non-ionomer, or a blend ofmaterials, and the outer layer may be a harder material such as a harderionomer, non-ionomer, or blend of materials.

Moreover, in alternative embodiments, either the inner and/or the outercover layer (or single cover layer, if applicable) may also additionallycomprise up to 100 wt % of a soft, low modulus, non-ionomericthermoplastic or thermoset material. Non-ionomeric materials aresuitable so long as they produce the playability and durabilitycharacteristics desired without adversely affecting the properties ofthe cover layer(s). These include, but are not limited to,styrene-butadiene-styrene block copolymers, including functionalizedstyrene-butadiene-styrene block copolymers,styrene-ethylene-butadiene-styrene (SEBS) block copolymers such asKraton® materials from Shell Chem. Co., and functionalized SEBS blockcopolymers; metallocene catalyzed polyolefins; ionomer/rubber blendssuch as those in Spalding U.S. Pat. Nos. 4,986,545; 5,098,105 and5,187,013; and, Hytrel® polyester elastomers from DuPont and Pebax®polyetheramides from Elf Atochem S. A.

The outer cover layer of the invention is formed over a core (and innercover layer or layers if a multi-layer cover) to result in a golf ballhaving a coefficient of restitution of at least 0.770, more preferablyat least 0.780, and most preferably at least 0.790. The coefficient ofrestitution of the ball will depend upon the properties of both the coreand the cover. The PGA compression of the golf ball is 100 or less, andpreferably is 90 or less.

In one preferred embodiment, the outer cover layer comprises apolyurethane, a polyurea or a blend of polyurethanes/polyureas.Polyurethanes are polymers which are used to form a broad range ofproducts. They are generally formed by mixing two primary ingredientsduring processing. For the most commonly used polyurethanes, the twoprimary ingredients are a polyisocyanate (for example,4,4′-diphenylmethane diisocyanate monomer (“MDI”) and toluenediisocyanate (“TDI”) and their derivatives) and a polyol (for example, apolyester polyol or a polyether polyol).

A wide range of combinations of polyisocyanates and polyols, as well asother ingredients, are available. Furthermore, the end-use properties ofpolyurethanes can be controlled by the type of polyurethane utilized,such as whether the material is thermoset (cross linked molecularstructure not flowable with heat) or thermoplastic (linear molecularstructure flowable with heat).

Cross linking occurs between the isocyanate groups (—NCO) and thepolyol's hydroxyl end-groups (—OH). Cross linking will also occurbetween the NH₂ group of the amines and the NCO groups of theisocyanates, forming a polyurea. Additionally, the end-usecharacteristics of polyurethanes can also be controlled by differenttypes of reactive chemicals and processing parameters. For example,catalysts are utilized to control polymerization rates. Depending uponthe processing method, reaction rates can be very quick (as in the casefor some reaction injection molding systems (“RIM”)) or may be on theorder of several hours or longer (as in several coating systems such asa cast system). Consequently, a great variety of polyurethanes aresuitable for different end-uses.

Polyurethanes are typically classified as thermosetting orthermoplastic. A polyurethane becomes irreversibly “set” when apolyurethane prepolymer is cross linked with a polyfunctional curingagent, such as a polyamine or a polyol. The prepolymer typically is madefrom polyether or polyester. A prepolymer is typically an isocyanateterminated polymer that is produced by reacting an isocyanate with amoiety that has active hydrogen groups, such as a polyester and/orpolyether polyol. The reactive moiety is a hydroxyl group. Diisocyanatepolyethers are preferred because of their water resistance.

The physical properties of thermoset polyurethanes are controlledsubstantially by the degree of cross linking and by the hard and softsegment content. Tightly cross linked polyurethanes are fairly rigid andstrong. A lower amount of cross linking results in materials that areflexible and resilient. Thermoplastic polyurethanes have some crosslinking, but primarily by physical means, such as hydrogen bonding. Thecrosslinking bonds can be reversibly broken by increasing temperature,such as during molding or extrusion. In this regard, thermoplasticpolyurethanes can be injection molded, and extruded as sheet and blowfilm. They can be used up to about 400° F. and are available in a widerange of hardnesses.

Polyurethane materials suitable for the present invention may be formedby the reaction of a polyisocyanate, a polyol, and optionally one ormore chain extenders. The polyol component includes any suitablepolyether- or polyester polyol. Additionally, in an alternativeembodiment, the polyol component is polybutadiene diol. The chainextenders include, but are not limited to, diols, triols and amineextenders. Any suitable polyisocyanate may be used to form apolyurethane according to the present invention. The polyisocyanate ispreferably selected from the group of diisocyanates including, but notlimited to, 4,4′-diphenylmethane diisocyanate (“MDI”); 2,4-toluenediisocyanate (“TDI”); m-xylylene diisocyanate (“XDI”); methylenebis-(4-cyclohexyl isocyanate) (“HMDI”); hexamethylene diisocyanate(“HDI”); naphthalene-1,5,-diisocyanate (“NDI”);3,3′-dimethyl-4,4′-biphenyl diisocyanate (“TODI”); 1,4-diisocyanatebenzene (“PPDI”); phenylene-1,4-diisocyanate; and 2,2,4- or2,4,4-trimethyl hexamethylene diisocyanate (“TMDI”).

Other less preferred diisocyanates include, but are not limited to,isophorone diisocyanate (“IPDI”); 1,4-cyclohexyl diisocyanate (“CHDI”);diphenylether-4,4′-diisocyanate; p,p′-diphenyl diisocyanate; lysinediisocyanate (“LDI”); 1,3-bis (isocyanato methyl) cyclohexane; andpolymethylene polyphenyl isocyanate (“PMDI”).

One additional polyurethane component which can be used in the presentinvention incorporates TMXDI (“META”) aliphatic isocyanate (CytecIndustries, West Paterson, N.J.). Polyurethanes based onmeta-tetramethylxylylene diisocyanate (TMXDI) can provide improved glossretention UV light stability, thermal stability, and hydrolyticstability. Additionally, TMXDI (“META”) aliphatic isocyanate hasdemonstrated favorable toxicological properties. Furthermore, because ithas a low viscosity, it is usable with a wider range of diols (topolyurethane) and diamines (to polyureas). If TMXDI is used, ittypically, but not necessarily, is added as a direct replacement forsome or all of the other aliphatic isocyanates in accordance with thesuggestions of the supplier. Because of slow reactivity of TMXDI, it maybe useful or necessary to use catalysts to have practical demoldingtimes. Hardness, tensile strength and elongation can be adjusted byadding further materials in accordance with the supplier's instructions.

The polyurethane which is selected for use as a golf ball coverpreferably has a Shore D hardness (plaque) of from about 10 to about 55(Shore C of about 15 to about 75), more preferably from about 25 toabout 55 (Shore C of about 40 to about 75), and most preferably fromabout 30 to about 55 (Shore C of about 45 to about 75) for a soft coverlayer and from about 20 to about 90, preferably about 30 to about 80,and more preferably about 40 to about 70 for a hard cover layer.

The polyurethane which is to be used for a cover layer preferably has aflex modulus from about 1 to about 310 Kpsi, more preferably from about3 to about 100 Kpsi, and most preferably from about 3 to about 40 Kpsifor a soft cover layer and 40 to 90 Kpsi for a hard cover layer.Accordingly, covers comprising these materials exhibit similarproperties. The polyurethane preferably has good light fastness.

Non-limiting examples of a polyurethane suitable for use in the outercover layer (or inner cover layer) include a thermoplastic polyesterpolyurethane such as Bayer Corporation's Texin® polyester polyurethane(such as Texin® DP7-1097 and Texin® 285 grades) and a polyesterpolyurethane such as B. F. Goodrich Company's Estane® polyesterpolyurethane (such as Estane® X-4517 grade). The thermoplasticpolyurethane material may be blended with a soft ionomer or othernon-ionomer. For example, polyamides blend well with soft ionomer.

Other soft, relatively low modulus non-ionomeric thermoplastic orthermoset polyurethanes may also be utilized to produce the outer coverlayers, or any of the inner cover layers, as long as the non-ionomericmaterials produce the playability and durability characteristics desiredwithout adversely affecting the enhanced travel distance characteristicproduced by the high acid ionomer resin composition. These include, butare not limited to thermoplastic polyurethanes such as the Pellethaneethermoplastic polyurethanes from Dow Chemical Co.; and non-ionomericthermoset polyurethanes including but not limited to those disclosed inU.S. Pat. No. 5,334,673 incorporated herein by reference.

Typically, there are two classes of thermoplastic polyurethanematerials: aliphatic polyurethanes and aromatic polyurethanes. Thealiphatic materials are produced from a polyol or polyols and aliphaticisocyanates, such as H₁₂MDI or HDI, and the aromatic materials areproduced from a polyol or polyols and aromatic isocyanates, such as MDIor TDI. The thermoplastic polyurethanes may also be produced from ablend of both aliphatic and aromatic materials, such as a blend of HDIand TDI with a polyol or polyols.

Generally, the aliphatic thermoplastic polyurethanes are lightfast,meaning that they do not yellow appreciably upon exposure to ultravioletlight. Conversely, aromatic thermoplastic polyurethanes tend to yellowupon exposure to ultraviolet light. One method of stopping the yellowingof the aromatic materials is to paint the outer surface of the finishedball with a coating containing a pigment, such as titanium dioxide, sothat the ultraviolet light is prevented from reaching the surface of theball. Another method is to add UV absorbers, optical brighteners andstabilizers to the clear coating(s) on the outer cover, as well as tothe thermoplastic polyurethane material itself. By adding UV absorbersand stabilizers to the thermoplastic polyurethane and the coating(s),aromatic polyurethanes can be effectively used in the outer cover layerof golf balls. This is advantageous because aromatic polyurethanestypically have better scuff resistance characteristics than aliphaticpolyurethanes, and the aromatic polyurethanes typically cost less thanthe aliphatic polyurethanes.

Other suitable polyurethane materials for use in the present inventiongolf balls include reaction injection molded (“RIM”) polyurethanes. RIMis a process by which highly reactive liquids are injected into a mold,mixed usually by impingement and/or mechanical mixing in an in-linedevice such as a “peanut mixer,” where they polymerize primarily in themold to form a coherent, one-piece molded article. The RIM processusually involves a rapid reaction between one or more reactivecomponents such as a polyether polyol or polyester polyol, polyamine, orother material with an active hydrogen, and one or moreisocyanate-containing constituents, often in the presence of a catalyst.The constituents are stored in separate tanks prior to molding and maybe first mixed in a mix head upstream of a mold and then injected intothe mold. The liquid streams are metered in the desired weight to weightratio and fed into an impingement mix head, with mixing occurring underhigh pressure, for example, 1,500 to 3,000 psi. The liquid streamsimpinge upon each other in the mixing chamber of the mix head and themixture is injected into the mold. One of the liquid streams typicallycontains a catalyst for the reaction. The constituents react rapidlyafter mixing to gel and form polyurethane polymers. Polyureas, epoxies,and various unsaturated polyesters also can be molded by RIM.

Non-limiting examples of suitable RIM systems for use in the presentinvention are Bayflex® elastomeric polyurethane RIM systems, Baydur® GSsolid polyurethane RIM systems, Prism® solid polyurethane RIM systems,all from Bayer Corp. (Pittsburgh, Pa.), Spectrim® reaction moldablepolyurethane and polyurea systems from Dow Chemical USA (Midland,Mich.), including Spectrim® MM 373-A (isocyanate) and 373-B (polyol),and Elastolit® SR systems from BASF (Parsippany, N.J.). Preferred RIMsystems include Bayflex® MP-10000, Bayflex® MP-7500 and Bayflex® 110-50,filled and unfilled. Further preferred examples are polyols, polyaminesand isocyanates formed by processes for recycling polyurethanes andpolyureas. Additionally, these various systems may be modified byincorporating a butadiene component in the diol agent.

Another preferred embodiment is a golf ball in which at least one of theinner cover layer and/or the outer cover layer comprises afast-chemical-reaction-produced component. This component comprises atleast one material selected from the group consisting of polyurethane,polyurea, polyurethane ionomer, epoxy, and unsaturated polyesters, andpreferably comprises polyurethane, polyurea or a blend comprisingpolyurethanes and/or polymers. A particularly preferred form of theinvention is a golf ball with a cover comprising polyurethane or apolyurethane blend.

The polyol component typically contains additives, such as stabilizers,flow modifiers, catalysts, combustion modifiers, blowing agents,fillers, pigments, optical brighteners, and release agents to modifyphysical characteristics of the cover. Polyurethane/polyurea constituentmolecules that were derived from recycled polyurethane can be added inthe polyol component.

A golf ball inner cover layer or single cover layer according to thepresent invention formed from a polyurethane material typically containsfrom about 0 to about 60 weight percent of filler material, morepreferably from about 1 to about 30 weight percent, and most preferablyfrom about 1 to about 20 weight percent.

A golf ball outer cover layer according to the present invention formedfrom a polyurethane material typically contains from about 0 to about 20weight percent of filler material, more preferably from about 1 to about10 weight percent, and most preferably from about 1 to about 5 weightpercent.

Additional materials may also be added to the inner and outer coverlayer of the present invention as long as they do not substantiallyreduce the playability properties of the ball. Such materials includedyes and/or optical brighteners (for example, Ultramarine Blue™ sold byWhittaker, Clark, and Daniels of South Plainsfield, N.J.) (see U.S. Pat.No. 4,679,795); pigments such as titanium dioxide, zinc oxide, bariumsulfate and zinc sulfate; UV absorbers; antioxidants; antistatic agents;and stabilizers. Moreover, the cover compositions of the presentinvention may also contain softening agents such as those disclosed inU.S. Pat. Nos. 5,312,857 and 5,306,760, including plasticizers, metalstearates, processing acids, and the like, and reinforcing materialssuch as glass fibers and inorganic fillers, as long as the desiredproperties produced by the golf ball covers of the invention are notimpaired.

Core Layer(s)

The core of the golf ball can be formed of a solid, a liquid, or anyother substance that will result in a core or an inner ball (core and atleast one inner cover layer, if the ball is a multi-layer ball), havingthe desired COR, compression and hardness and other physical properties.

The cores of the inventive golf balls typically have a coefficient ofrestitution of about 0.750 or more, more preferably 0.770 or more and aPGA compression of about 90 or less, and more preferably 70 or less.Furthermore, in some applications it may be desirable to provide a corewith a coefficient of restitution of about 0.780 to 0.790 or more.

The core used in the golf ball of the invention preferably is a solid,but any core type known in the art may be used, such as wound, liquid,hollow, metal, and the like. The term “solid cores” as used hereinrefers not only to one piece cores but also to those cores having aseparate solid layer beneath the covers and over the central core. Thecores generally have a weight of about 25 to about 40 grams andpreferably about 30 to about 40 grams. Larger and heavier cores, orlighter and smaller cores, may also be used when there is no desire tomeet U.S.G.A. or R. & A. standards.

When the golf ball of the invention has a solid core, this core can becompression molded from a slug of uncured or lightly cured elastomercomposition comprising a high cis content polybutadiene and a metal saltof an α, β, ethylenically unsaturated carboxylic acid such as zinc mono-or diacrylate or methacrylate. To achieve higher coefficients ofrestitution and/or to increase hardness in the core, the manufacturermay include a small amount of a metal oxide such as zinc oxide. Inaddition, larger amounts of metal oxide than are needed to achieve thedesired coefficient may be included in order to increase the core weightso that the finished ball more closely approaches the U.S.G.A. upperweight limit of 1.620 ounces.

Non-limiting examples of other materials which may be used in the corecomposition include, but are not limited to, compatible rubbers orionomers, and low molecular weight fatty acids such as stearic acid.Free radical initiator catalysts such as peroxides may be admixed withthe core composition so that on the application of heat and pressure, acuring or cross-linking reaction takes place. The core may also beformed from any other process for molding golf ball cores known in theart.

A thread wound core may comprise a liquid, solid, gel or multi-piececenter. The thread wound core is typically obtained by winding a threadof natural or synthetic rubber, or thermoplastic or thermosettingelastomer such as polyurethane, polyester, polyamide, etc. on a solid,liquid, gel or gas filled center to form a thread rubber layer that isthen covered with one or more mantle or cover layers. Additionally,prior to applying the cover layer(s), the thread wound core may befurther treated or coated with an adhesive layer, protective layer, orany substance that may improve the integrity of the wound core duringapplication of the cover layers and ultimately in usage as a golf ball.

Since the core material is not an integral part of the presentinvention, a detailed discussion concerning the specific types of corematerials which may be utilized with the cover compositions of theinvention are not specifically set forth herein.

Manufacturing Golf Balls

The golf balls of the present invention eliminate or reduce the need forretractable pins to support the core (or core and inner cover layer(s))in the mold. There may be, however, “knock out” pins in the mold thatare useful in extracting the part from the mold. In the prior art,retractable pins have been used to support the core or core andadditional layers. The pins hold the core in place until enough covermaterial fills the mold to support the core without assistance, at whichtime the pins are retracted. Molding golf balls without the use ofretractable pins reduces the amount of additional processing necessaryon a finished ball. Additionally, there is no need to clean the moldfrequently because of build up of cover material on the retractable moldpins.

In accordance with a preferred technique of the invention, one or moredeep dimples are formed that extend to or into various internal layersor components of a golf ball. Specifically, each layer has dimplesformed therein by a dimpled cavity having a pattern having the samegeometric coordinates as other corresponding dimpled cavities. The coreor core and inner layer(s) need to be aligned such that the dimples areformed over one another in the subsequent layers.

For example, for a dimple in a preferred embodiment ball of the presentinvention, the outer layer may account for a portion of the total depth,and the inner layer(s) will account for the remainder. In a traditionalprior art ball, the dimple depth, which is generally about 0.010 inches,is generally less than the thickness of the cover so that the dimpledoes not touch or extend to the next layer or even come close to thenext layer. Therefore, there is a minimum cover thickness that can beused in order to have dimples of the desired depth. The golf ball of thepresent invention eliminates the need to have a cover thickness greaterthan the desired dimple depth because two or more layers can make up thedimple, and thus, each layer may be very thin (less than 0.010 inches).

Furthermore, the golf balls of the present invention may incorporateboth deep dimples and dual dimples (dimple within a dimple) or dimplesformed in multiple layers, as previously described.

In preparing golf balls in accordance with a preferred embodiment of thepresent invention, a single cover layer or an inner cover layer (ormantle layer) is molded about a core (preferably a solid core). Thecover layer(s) may be molded using any molding processing known in theart. Examples of molding processes include, but are not limited to,injection molding, transfer molding, reaction injection molding, liquidinjection molding, casting, compression molding, and the like.

For a multi-layer ball, as shown in FIGS. 3 and 4, an outer layer 160 ismolded over the inner layer 150. The core (or core and inner layer(s))is supported by one or more, preferably two or more, support pins orprotrusions which form the deep dimples that contact the core orintermediate ball assembly. That is, the exterior surface of the supportpins or protrusions form the inner surface of the deep dimples.

The core (or core and inner layer(s)) is held in place by a holdingforce created by designing the dimples, or rather the raised projectionson a molding surface that form such dimples, deep enough to grip theball by slightly pre-loading the core or intermediate ball assembly.Ignoring friction, the only force generated is in the radial direction,and radial pre-load force is proportional to radial interference betweenthe deep dimples and the core or core and inner layer(s).

The number of deep dimples on a golf ball of the present invention mayvary as desired. Any number and pattern of deep dimples may be used,although a limited number of deep dimples in a specific geometricpattern is preferred. The geometric pattern is preferably approximatelycentered about the pole of the ball. Given the limited number ofcoordinates or points, it is generally not possible to exactly centercertain geometric patterns with some shapes, such as a triangle.Additionally, it may be desirable to shift the pattern slightly toaccommodate different forces (due to the molding of the layer(s)) ondifferent sides of the ball.

FIGS. 9 and 10 are top views (one hemisphere of the ball) of a golf ballhaving certain preferred arrangements of deep dimples. FIG. 9illustrates a golf ball 610 having a triangular arrangement of threedeep dimples 42 located approximately symmetrically around a pole 44.FIG. 10 illustrates a golf ball 710 having a diamond shaped arrangementof four deep dimples 42 located approximately symmetrically around apole 44. The figures are for illustrative purposes since any desirednumber of deep dimples may be used, such as one, two, three, four, five,six and the like. The deep dimples do not have to be symmetricallylocated, although symmetry enhances their aerodynamic effect. Thisresults in a finished ball where the deep dimples extend from the outerlayer into the next inner layer(s) and/or the core. Multiple coverlayers, of the same or different materials and thicknesses, may be addedto the ball using this procedure. The deep dimples may extend intomultiple layers if there are multiple layers on the ball, if desired.

The deep dimple locations may be anywhere on the ball, such as at about30 degrees latitude on each hemisphere, about 40 to 45 degrees latitude,about 50 to 60 degrees latitude, and the like. That is, the deep dimplesmay be within a region along the outer surface of a ball from about 30degrees latitude to about 60 degrees latitude in either or bothhemispheres. Preferably, the deep dimples are located at about 40 to 45degrees latitude or more on each hemisphere. As used herein, latituderefers to the location of the dimple on the ball, with the equatordefined as 0 degrees latitude, and each pole of the ball defined as 90degrees latitude.

FIG. 13 is a graph illustrating the relationship between the location ofthese deep dimples on a ball and the resulting force applied to thecore. Table 1, set forth below lists the data that is illustratedgraphically in FIG. 13.

TABLE 1 Angle Lateral Vertical deg % Radial % Radial 0 100%  0% 5 100% 9% 10  98%  17% 15  97%  26% 20  94%  34% 25  91%  42% 30  87%  50% 35 82%  57% 40  77%  64% 45  71%  71% 50  64%  77% 55  57%  82% 60  50% 87% 65  42%  91% 70  34%  94% 75  26%  97% 80  17%  98% 85  9% 100% 90 0% 100% Notes 1. Cavity with no retractable core pins 2. Core issupported by 3 or more deep dimples that contact the core 3. Force iscreated by designing the deepest dimple to pre-load core slightly 4. Theonly force generated is in the radial direction (all force vectors passthrough ball center) 5. Radial pre-load force is proportional to radialinterference between deepest dimples & core 6. If core is undersized,there is no pre-load force 7. Friction is ignored.

In another preferred embodiment, the core or intermediate ball (coreplus one or more mantle or inner cover layer(s)) is supported by one ormore deep dimples that nearly contact or extend to the core. The deepdimple locations may be anywhere on the ball, such as at about 30degrees latitude on each hemisphere, about 40 to 45 degrees latitude,about 50 to 60 degrees latitude, and the like. Preferably, the deepdimples are located at about 40 to 45 degrees latitude or more on eachhemisphere. The number of deep dimples may vary as desired. Any numberand pattern may be used, although a limited number in a specificgeometric pattern is preferred. The geometric pattern should preferablybe approximately centered about the pole of the ball. It is not possibleto exactly center the geometric pattern with some shapes, such as atriangle. Additionally, it may be desirable to shift the patternslightly to accommodate different forces (due to the molding of thelayer(s)) on different sides of the ball. This results in a finishedball where the deep dimples extend from the outer layer to the nextinner layer or the core. As described above, multiple cover layers, ofthe same or different materials and thicknesses, may be added to theball using this procedure.

FIG. 14 is a perspective view of a preferred embodiment golf ballaccording to the present invention. This illustration reveals acircumferential region defined along the outer surface of the ball. Thisregion corresponds to the preferred location within which are definedone or more deep dimples as described herein. Specifically, thepreferred location for the deep dimples is the region along the outersurface of the ball extending between about 30° latitude and about 60°latitude. The pole of the ball is an axis extending through the ballshown in FIG. 14 as line P—P. The equator is illustrated in FIG. 14 as acircumferential line E extending about the ball at a latitude of 0°.

Any number of cover and/or mantle layers may be used, and the deepdimples may extend into as many layers as desired. For example, a golfball having a core and three cover layers (a first inner cover layer, asecond inner cover layer, and an outer cover layer) may be producedaccording to the present invention. The deep dimples may extend to orthrough the first inner cover layer, through both the first inner layerand the second inner cover layer, or, the deep dimple may extend throughall the cover layers to or into the core.

Additionally, if desired, the mantle layer could be colored or containother visible or cosmetic features that could be seen through the coverlayer. The cover layer may also be transparent, translucent or opaque ifdesired to enhance or highlight the mantle layer.

Other methods of molding golf balls without the use of core pins includethe use of tabs on the equator of the core such that the dimpled cavitycan receive the tabs to hold the core in place. Alternatively, the golfball may be molded with a mantle having one or more keyways or openings.The cover mold would then be equipped with side pulls that engage thekeys and hold the core in place.

The core, preferably a solid core, for the ball is preferably about 1.2to about 1.6 inches in diameter, although it may be possible to usecores in the range of about 1.0 to 2.0 inches. If the ball has a singlecover layer, the core size may be up to about 1.660 inches.

The present invention includes one or more auxiliary layers disposed onthe core, and preferably immediately adjacent to the outer core surface.For example, for some applications, it may be preferred to deposit abarrier coating that limits transmission of moisture to the core. Aspreviously noted, such barrier coatings or layers are relatively thin.Generally, such coatings are at least 0.0001 inches, and preferably, atleast 0.003 inches in thickness. Furthermore, an adhesion promotinglayer may be used between the cover layers and/or the core, or the coverand core having a barrier coating disposed thereon. Such adhesionpromoting layers are known in the art and may be used in combinationwith the inventive features described herein. See for example U.S. Pat.No. 5,820,488 herein incorporated by reference.

The inner cover layer that is molded over the core is preferably about0.0005 inches to about 0.15 inches. The inner ball that includes thecore and inner cover layer(s), or core for a two piece ball, preferablyhas a diameter in the range of 1.25 to 1.60 inches. The outer coverlayer is about 0.0005 inches to about 0.15 inches thick. Together, thecore, the inner cover layer(s) and the outer cover layer (or core andsingle cover layer) combine to form a ball having a diameter of 1.680inches or more, the minimum diameter permitted by the rules of theU.S.G.A and weighing no more than 1.62 ounces. If desired, golf balls ofdifferent weights and diameters may also be formed if the rules of theU.S.G.A. are not an issue.

In a particularly preferred embodiment of the invention, the golf ballhas a dimple pattern that provides dimple coverage of 65% or more,preferably 75% or more, and more preferably about 80 to 85% or more. Ina preferred embodiment of the invention, there are from 300 to less than500 dimples, preferably from about 340 to about 440 dimples.

Specifically, the arrangement and total number of dimples are notcritical and may be properly selected within ranges that are well known.For example, the dimple arrangement may be an octahedral, dodecahedralor icosahedral arrangement. The total number of dimples is generallyfrom about 250 to about 600, and especially from about 300 to about 500.

In a preferred embodiment, the golf ball typically is coated with adurable, abrasion-resistant, relatively non-yellowing finish coat orcoats if necessary. The finish coat or coats may have some opticalbrightener and/or pigment added to improve the brightness of thefinished golf ball. In a preferred embodiment, from 0.001 to about 10%optical brightener may be added to one or more of the finish coatings.If desired, optical brightener may also be added to the cover materials.One type of preferred finish coatings are solvent based urethanecoatings known in the art. It is also contemplated to provide atransparent outer coating or layer on the final finished golf ball.

Golf balls also typically include logos and other markings printed ontothe dimpled spherical surface of the ball. Paint, typically clear paint,is applied for the purposes of protecting the cover and improving theouter appearance before the ball is completed as a commercial product.FIG. 11 is a fragmental enlarged view showing the radial cross-sectionalshape of a dimple formed in the surface of a golf ball prior to paintcoating. Most often, the dimple is circular in plane shape. In general,dimples such as the deep dimples shown in FIG. 11, are formed in a golfball surface as a recess or indentation. The cross-sectional shape of adimple is defined by a portion of a curved surface such as a circle,ellipse, or hyper ellipse. For example, the cross-sectional shape of thedimple in FIG. 11 is a portion of a circle. The dimple is circumscribedby an upper edge which is continuously connected to a land area of theouter surface of the golf ball where no dimples are formed. The edge isgenerally beveled from the land area as a steep slope to form thedimple. The edge is generally initially angular prior to paint coatingand somewhat rounded after paint coating.

The various cover composition layers of the present invention may beproduced according to conventional melt blending procedures or any othermethod known in the art. For example, the cover materials may be blendedin a Banbury® type mixer, two-roll mill, or extruder prior toneutralization. After blending, neutralization then occurs in the meltor molten state in the Banbury® mixer. The blended composition is thenformed into slabs, pellets, etc., and maintained in such a state untilmolding is desired. Alternatively, a simple dry blend of the pelletizedor granulated materials (which have previously been neutralized to adesired extent, if applicable) and colored master batch may be preparedand fed directly into the injection molding machine where homogenizationoccurs in the mixing section of the barrel prior to injection into themold. If necessary, further additives such as an inorganic filler, etc.,may be added and uniformly mixed before initiation of the moldingprocess.

The golf balls of the present invention can be produced by moldingprocesses which include, but are not limited to, those which arecurrently well known in the golf ball art. As mentioned above, the golfballs can be produced, for example, by injection molding, reactioninjection molding (RIM), liquid injection molding, compression molding,and the like, the novel cover compositions around a wound, solid orother type of core to produce an inner ball which typically has adiameter of about 1.50 to 1.67 inches.

Alternatively, the cover layer(s) may be cast around the core or coreand inner layer(s), such as in a cast polyurethane system. The outerlayer is subsequently molded over the inner layer to produce a golf ballhaving a diameter of 1.620 inches or more, preferably about 1.680 inchesor more. This is currently a less preferred process since it is moredifficult to cast mold around the deep dimple protrusions. Although anytype of core, such as either solid cores or wound cores can be used inthe present invention, as a result of is their lower cost and superiorperformance, solid molded cores are preferred over wound cores. Thestandards for both the minimum diameter and maximum weight of the ballsare established by the United States Golf Association (U.S.G.A.), butnot all golf balls are designed to meet these standards.

In compression molding, smooth surfaced hemispherical shells (previouslymolded) are positioned around the core in a mold having the desiredinner cover thickness. The core and shells are then subjected tocompression molding at about 200° F. to 300° F. for about 2 to 10minutes, followed by cooling at 50° F. to 70° F. for about 2 to 7minutes to fuse the shells together to form a unitary intermediate ball.In addition, the intermediate balls may be produced by injection moldingwherein the inner cover layer is injected directly around the coreplaced at the center of an intermediate ball mold for a period of timein a mold temperature of from 50° F. to about 100° F. Subsequently, theouter cover layer is molded about the core and the inner layer bysimilar molding techniques to form a dimpled golf ball of a diameter of1.680 inches or more. To improve the adhesion between the inner coverlayer and the outer cover layer, or any of the cover layers and/or thecore, an adhesion promoter may be used. Some adhesion promoters, such asabrasion of the surface, corona treatment, and the like, are known inthe art. A preferred adhesion promoter is a chemical adhesion promoter,such as a silane or other silicon compound, preferablyN-(2-aminoethyl-3)-aminopropyltrimethoxysilane. The intermediate golfball (core and inner cover layer) may be dipped or sprayed with thechemical, and then the outer cover layer is formed over the treatedinner cover layer. For multiple cover layers, the ball may be treatedmore than once if necessary or desired.

A typical process for casting covers around a core or core and innerlayer(s) comprises two part (for example, bookcase type) molds that areheated to approximately 80 to 180° F. The cover material, such as apolyurethane, is heated to approximately 80 to 180° F. The material geltime is approximately 20 to 90 seconds, and mold closure time (heatstep) is approximately 2 to 8 minutes, and the cooling step isapproximately 2 to 8 minutes. After the material forms a cover, themolds are opened, and the balls are removed from the molds. The cavitiesmay optionally be cleaned and/or coated with a mold release before theprocess is repeated.

After molding, the golf balls produced may undergo various furtherprocessing steps such as buffing, trimming, milling, tumbling, paintingand marking as disclosed in U.S. Pat. No. 4,911,451, herein incorporatedby reference.

The resulting golf ball is produced more efficiently and lessexpensively than balls of the prior art. Additionally, the golf balls ofthe present invention may have multiple cover layers, some of them verythin (less than 0.03 inches, more preferably less than 0.02 inches, evenmore preferably less than 0.01 inches) if desired, to produce golf ballshaving specific performance characteristics. For example, golf ballshaving softer outer cover layer(s) and harder inner cover layer(s) maybe produced. Alternatively, golf balls having harder outer coverlayer(s) and softer inner cover layer(s) may be produced. Moreover, golfballs having inner and outer cover layers with similar hardnesses arealso anticipated by the present invention.

For golf balls have three or more layers, the hardness of the layers maybe varied alternately, such as hard-soft-hard, or soft-hard-soft, andthe like, or golf balls with a cover having a hardness gradient may beproduced. The hardness gradient may start with hard inner layers closestto the core and get softer at the outer layer, or vice versa. Thisallows a lot of flexibility and control of finished golf ballproperties. As previously described, the layers may be of the same ordifferent materials, and of the same or different thicknesses.

Additionally, golf balls of the present invention that comprisepolyurethane/polyurea (or other suitable materials) in any of the innerand outer cover layer may be produced by a reaction injection moldingprocess (RIM), as previously described.

Golf balls and, more specifically, cover layers formed by RIM arepreferably formed by the process described in application Ser. No.09/040,798, filed Mar. 18, 1998, incorporated herein by reference, or bya similar RIM process.

RIM differs from non-reaction injection molding in a number of ways. Themain distinction is that in RIM a chemical reaction takes place in themold to transform a monomer or adducts to polymers and the componentsare in liquid form. Thus, a RIM mold need not be made to withstand thepressures that occur in conventional injection molding.

In contrast, injection molding is conducted at high molding pressures inthe mold cavity by melting a solid resin and conveying it into a mold,with the molten resin often being at about 150 to about 350° C. At thiselevated temperature, the viscosity of the molten resin usually is inthe range of about 50,000 to about 1,000,000 centipoise, and istypically around 200,000 centipoise. In an injection molding process,the solidification of the resins occurs after about 10 to about 90seconds, depending upon the size of the molded product, the temperatureand heat transfer conditions, and the hardness of the injection moldedmaterial. Subsequently, the molded product is removed from the mold.There is no significant chemical reaction taking place in an injectionmolding process when the thermoplastic resin is introduced into themold.

In contrast, in a RIM process, the chemical reaction causes the materialto set in less than about 5 minutes, often in less than 2 minutes,preferably in less than one minute, more preferably in less than 30seconds, and in many cases in about 10 seconds or less.

Catalysts can be added to the RIM polyurethane system starting materialsas long as the catalysts generally do not react with the constituentwith which they are combined. Suitable catalysts include those which areknown to be useful with polyurethanes and polyureas.

The polyol component typically contains additives, such as stabilizers,flow modifiers, catalysts, combustion modifiers, blowing agents,fillers, pigments, optical brighteners, and release agents to modifyphysical characteristics of the cover. Recycled polyurethane/polyureaalso can be added to the core. Polyurethane/polyurea constituentmolecules that were derived from recycled polyurethane can be added inthe polyol component.

The mold cavity contains support pins and is generally constructed inthe same manner as a mold cavity used to injection mold a thermoplastic,for example, ionomeric golf ball cover. However, two differences whenRIM is used are that tighter pin tolerances generally are required, anda lower injection pressure is used. Also, the molds can be produced fromlower strength material such as aluminum.

The RIM process may provide for improved cover layers. If plasticproducts are produced by combining components that are preformed to someextent, subsequent failure can occur at a location on the cover which isalong the seam or parting line of the mold, as well as at core pinlocations, because these regions are intrinsically different from theremainder of the cover layer and can be weaker or more stressed. Coverlayers produced via RIM are believed to provide for improved durabilityof a golf ball cover layer by providing a uniform or “seamless” cover inwhich the properties of the cover material in the region along theparting line are generally the same as the properties of the covermaterial at other locations on the cover, including at the poles. Theimprovement in durability is believed to be a result of the fact thatthe reaction mixture is distributed uniformly into a closed mold. Thisuniform distribution of the injected materials reduces or eliminatesknit-lines and other molding deficiencies which can be caused bytemperature differences and/or reaction differences in the injectedmaterials. RIM typically results in generally uniform molecularstructure, density and stress distribution as compared to conventionalinjection-molding processes.

The golf balls, and particularly the cover layer(s), of the presentinvention may also be formed by liquid injection molding (LIM)techniques, or any other method known in the art.

The golf balls formed according to the present invention can be coatedusing a conventional two-component spray coating or can be coated duringthe RIM process, for example, using an in-mold coating process.

FIG. 15 illustrates a preferred embodiment molding apparatus 1000 inaccordance with the present invention. Molding apparatus 1000 comprisestwo mold halves 1020 and 1040 that each define a hemispherical portionof a molding chamber 1024 and 1044. Defined along the outer surface ofthe hemispherical portion of the molding chamber 1024, are a pluralityof raised protrusions or support pins 1032. These raised regions orsupport pins form dimples in a cover layer in a golf ball formed usingmolding apparatus 1000. Also provided along the outer surface of thehemispherical molding chamber 1024 are a plurality of raised regions orsupport pins 1026, 1028, and 1030. These raised regions are of a heightgreater than the height of the raised regions 1032. Specifically, theraised regions 1026, 1028, and 1030 form deep dimples as describedherein. These raised regions are used to retain and support a golf ballcore (or intermediate ball assembly) placed in the mold. A passage 1022is provided in the mold half 1020 as will be appreciated. The passage1022 provides communication and a path for a flowable moldable materialto be introduced into the molding chamber. The molding apparatus 1000also includes a second molding portion or plate 1040. The plate 1040defines a hemispherical molding chamber 1044 also having a plurality ofraised regions or support pins along its outer surface. Specifically,raised regions 1046 and 1048 are provided similar to the previouslydescribed raised regions 1026, 1028, and 1030. The molding plate 1040also defines a channel 1042 extending from the molding chamber 1044 tothe exterior of the plate. Most preferably, the molding channel 1042 isaligned with channel 1022 in the other plate 1020 when the mold isclosed to provide a unitary passage providing communication between themolding chamber and the exterior of the mold. A golf ball core placed inthe molding chamber 1020, 1040 is supported by the various raisedregions 1026, 1028, 1030, 1046, and 1048 as previously described. A golfball 1010 or ball component is produced.

In regards to forming a variety of golf balls, the present inventionalso provides a process for forming a golf ball having at least one deepdimple. Preferably, this process is as follows. An intermediate golfball assembly such as including a core or a core and/or one or moreintermediate layers disposed thereon, is provided. A molding apparatusis also provided for molding an outer or cover layer about theintermediate golf ball assembly. The molding apparatus includes agenerally spherical molding chamber having a first population orcollection of raised regions defined along a molding surface for forminga plurality of dimples on the outer layer of the golf ball. The moldingchamber also includes at least one other raised region or collection ofraised regions all of which have a height that is equal to or greaterthan the thickness of the outer layer to be formed on the golf ball. Theprocess also includes a step of positioning the intermediate golf ballassembly in the molding chamber and administering a flowable materialsuch as a flowable cover layer material to the molding apparatus. Thematerial is introduced such that it flows around the intermediate golfball assembly disposed in the molding chamber. Preferably, the processalso includes a step of hardening or curing the flowable material tothereby form the outer layer. A key feature of this technique is thatupon positioning the intermediate golf ball assembly in the moldingchamber, the other raised region(s) of the molding chamber contacts andpreferably supports the intermediate golf ball assembly while positionedwithin the molding chamber.

Specifically, the golf ball of the present invention is not particularlylimited with respect to its structure and construction. By using wellknown ball materials and conventional manufacturing processes, the ballsmay be manufactured as solid golf balls including one-piece golf balls,two-piece golf balls, and multi-piece golf balls with three or morelayers and wound golf balls.

The present invention is further illustrated by the following examplesin which the parts of the specific ingredients are by weight. It is tobe understood that the present invention is not limited to the examples,and various changes and modifications may be made in the inventionwithout departing from the spirit and scope thereof.

EXAMPLES

Golf balls according to the present invention were produced. The golfballs had a core, a mantle or inner cover layer, and an outer coverlayer. The mantle was an ionomer, and the outer cover was a polyurethanecover formed by a RIM process (Ball Type A). The mold used had 6 supportpins (3 in each hemisphere) which formed deep dimples in eachhemisphere, located in a triangular arrangement similar to that shown inFIG. 9. The balls were tested against other balls, as described below.The results are shown in Tables 3 to 5 below.

Ball Type B was a ball having a dual core, an ionomer mantle and ainjection molded polyurethane cover. Ball Type C was a ball having asingle core, an ionomer mantle and an ionomer cover. Ball Type D was acommercial grade Strata®) Tour Professional™ ball, Ball Type E was acommercial grade Top-Flite® Z-Balata™ 90 golf ball, Ball Type F was acommercial grade Nike® Tour Accuracy TW™ ball, and Ball Type G was acommercial grade Titleist® Pro VI™ ball.

Coefficient of restitution (C.O.R.) was measured by firing the resultinggolf ball in an air cannon at a velocity of 125 feet per second againsta steel plate positioned 12 feet from the muzzle of the cannon. Therebound velocity was then measured. The rebound velocity was divided bythe forward velocity to give the coefficient of restitution.

The scuff resistance test was conducted in the manner described below.The balls that were tested were primed and top coated. A sharp groovedsand wedge (56 degrees loft) was mounted in a mechanical swing machine.The club swing speed used was 60 mph. After each hit, the club face wasbrushed clean using a nylon bristled brush. A minimum of three samplesof each ball were tested. Each ball was hit three times at threedifferent locations so as not to overlap with other strikes. The detailsof the club face are critical, and are as follows:

Groove width—0.025 inches (cut with a mill cutter, leaving a sharp edgeto the groove; no sandblasting or post finishing should be done aftermilling);

Groove depth—0.016 inches;

Groove spacing (one groove edge to the nearest adjacent edge)—0.105inches.

For each strike, a point value should be assigned for the worst twodefects according to the following Table 2:

TABLE 2 Point Value Shear Defect 0 No visible defects 0.5 Lines 1 Lifts2 Bad Lifts 2 Tiny (or Paint) Hairs 3 Bad Hairs 3 Shears (if land areais removed on “hard” covers (65 Shore D+), rank as the only defect 6(max value) Bad Shears (dimples are completely removed, rank as the onlydefect)

Example—a strike having a shear, tiny hairs, bad lifts and a line wouldbe ranked as a 5 (3 points for a shear and 2 points for tiny hairs)Note: The maximum value per strike is 6.

After completing all strikes, the average point value was determined.This average point value, or rank, can be correlated to the chart below.

Rank Average Point Value Excellent 0.0-1.0 Very Good 1.1-2.0 Good2.1-3.0 Fair 3.1-4.0 Borderline 4.1-5.0 Poor (unacceptable) 5.1-6.0

Cut resistance was measured in accordance with the following procedure:A golf ball was fired at 135 feet per second against the leading edge ofa pitching wedge wherein the leading edge radius was {fraction (1/32)}inch, the loft angle was 51 degrees, the sole radius was 2.5 inches andthe bounce angle was 7 degrees.

The cut resistance of the balls tested herein was evaluated on a scaleof 1 to 5. The number 1 represents a cut that extends completely throughthe cover to the core. A 2 represents a cut that does not extendcompletely through the cover but that does break the surface. A 3 doesnot break the surface of the cover but does leave a permanent dent. A 4leaves only a slight crease which is permanent but not as severe as 3. A5 represents virtually no visible indentation or damage of any sort.

Cut and scuff testing was conducted on the golf balls of the invention(Ball Type A), two experimental golf balls (Ball Types B and C), and twocommercial grade golf balls (Ball Types F and G).

Initial velocity is the velocity of a ball when struck at a hammer speedof 143.8 feet per second in accordance with a test as prescribed by theU.S.G.A.

As used herein, “Shore D hardness” or “Shore C hardness” of a core orcover component is measured generally in accordance with ASTM D-2240,except the measurements are made on the curved surface of the moldedcomponent, rather than on a plaque. Furthermore, the Shore C and Dhardness of the cover is measured while the cover remains over the core.When a hardness measurement is made on a dimpled cover, Shore C or ShoreD hardness is measured at a land area of the dimpled cover.

Spin rate testing was conducted with the finished multi-layer golf balls(Ball Type A) of the invention, as well as two other experimentalmulti-layer cover golf balls (Ball Types B and C) using a driver, a 5iron, a 9 iron, and a pitching wedge.

For comparative purposes, two commercial grade golf balls (Ball Types Dand E) were also tested. The golf ball testing machine was set up toemulate the launch conditions of an average touring professional golferfor each particular club.

TABLE 3 Ball Constructions and Test Results Nez Ball Size Weight RiehleComp Fac- Cut Type (inches) (grams) Comp (PGA) COR tor Rank Scuff A1.683 45.5 80 80 0.801 881 3 4*  B 1.684 45.5 81 79 0.808 889 3 6   C1.685 45.4 79 81 0.808 887 3 5.8 D 1.684 45.4 80 80 0.800 880 — — E — —— — — — 5 6   F — — — — — — 2  2.7* *Defects were due to peeling ofpaint layers, not cover materials

Note that Ball Type A had cut and scuff results as good as, if notbetter than, most of the other ball types.

Below are the results of the spin rate and distance testing:

TABLE 4 Spin Rate Data (average for 12 hits per ball type) Launch TotalSpin Rate Ball Velocity Club Ball Type Angle (rpm) (ft./sec.) Hogan A10.3 2442 235.0 Prototype B 10.1 2776 236.0 Driver C 10.1 2776 236.5 D(Strata ® Tour 10.0 2660 235.4 Professional) E (Z-Balata 90) 10.0 2928230.8

TABLE 5 Distance Data (average for 12 hits per ball type) Peak FlightTotal Ball Trajec- Time Time Carry Roll Distance Club Type tory (sec)(sec) (yards) (yards) (yards) Hogan A 29.9 1.91 6.61 254.1 6.4 260.2Prototype B 30.4 1.99 6.84 258.8 5.3 264.0 Driver C 31.3 2.04 6.91 257.23.4 260.3 D 29.4 1.85 6.49 252.1 5.8 257.9 Top Flite A 46.6 1.93 6.47176.1 3.1 179.2 Tour ™ B 47.1 2.04 6.45 173.5 2.3 175.7 5 Iron C 47.42.08 6.51 173.5 1.6 175.1 D 45.6 1.96 6.49 177.1 2.4 179.5

Note that Ball Type A had results comparable to the other ball types.

The foregoing description is, at present, considered to be the preferredembodiments of the present invention. However, it is contemplated thatvarious changes and modifications apparent to those skilled in the artmay be made without departing from the present invention. Therefore, theforegoing description is intended to cover all such changes andmodifications encompassed within the spirit and scope of the presentinvention, including all equivalent aspects.

We claim:
 1. A golf ball comprising: a core; a mantle layer disposed onsaid core; and a cover layer disposed on said mantle layer, said coverlayer having an outer surface and defining a plurality of dimples alongsaid outer surface of said cover layer, at least one of said dimplesbeing defined by said cover layer, said mantle layer, and said core suchthat said dimple extends through maid cover layer to the mantle layer.2. The golf ball of claim 1, wherein said dimple extends through saidcover layer and said mantle layer.
 3. The golf ball of claim 1, whereinsaid dimple extends through said cover layer and said mantle layer, tosaid core.
 4. The golf ball of claim 3, wherein said dimple extendsthrough said cover layer and said mantle layer and into said core. 5.The golf ball of claim 1, wherein said cover layer includes an innercover layer disposed on said mantle layer and an outer cover layerdisposed on said inner cover layer.
 6. The golf ball of claim 1, whereinsaid dimple extending through said cover layer is located in a regiondefined within an outer surface hemisphere of said golf ball extendingbetween a 30 degree line of latitude and a 60 degree line of latitude.7. The golf ball of claim 1, wherein at least one of said mantle andsaid cover layer comprises an ionomeric material.
 8. The golf ball ofclaim 1, wherein at least one of said mantle and said cover layercomprises a polyurethane material.
 9. A golf ball comprising: a core;and a cover layer disposed about said core, said cover layer defining aplurality of dimples, at least a portion of said plurality of dimplesextending through said cover layer to said core, wherein said dimpleperiphery depth is from about 0.002 inches to about 0.140 inches. 10.The golf ball of claim 9, wherein said portion of said plurality ofdimples extend through said cover and into said core.
 11. The golf ballof claim 9, wherein said cover includes an inner cover layer disposed onsaid core and an outer cover layer disposed on said inner cover layer.12. The golf ball of claim 9, wherein said dimples extending throughsaid cover layer are located in a region defined within an outer surfacehemisphere of said golf ball extending between a 30 degree line oflatitude and a 60 degree line of latitude.
 13. The golf ball of claim 9,further comprising: a mantle layer disposed between said core and saidcover layer, wherein said portion of said plurality of dimples extendingthrough said cover layer also extends through said mantle layer.